Fabric.js Polygon lockScalingY Property

Last Updated : 01 Sep, 2020

In this article, we are going to see how to lock the vertical scaling of the canvas polygon using FabricJS. The canvas polygon means the polygon is movable and can be stretched according to requirement. Further, the polygon can be customized when it comes to initial stroke color, height, width, fill color, or stroke width.

To make it possible we are going to use a JavaScript library called FabricJS. After importing the library, we will create a canvas block in the body tag that will contain the polygon. After this, we will initialize instances of Canvas and polygon provided by FabricJS and lock vertical scaling of the canvas polygon using lockScalingY property and render the polygon on the Canvas as given in the example below.

Syntax:

fabric.Polygon([ 
    { x: pixel, y: pixel }, 
    { x: pixel, y: pixel }, 
    { x: pixel, y: pixel}, 
    { x: pixel, y: pixel}, 
    { x: pixel, y: pixel }],
    {
        lockScalingY: boolean
    });

Parameter: This property accepts a single parameter as mentioned above and described below:

lockScalingY: It specifies whether to lock the vertical scaling of the canvas.

Note: Dimension pixels is must to create a polygon.

Below examples illustrate the Fabric.JS Polygon lockScalingY property in JavaScript:

Example 1: In this example, lockScalingY value is set to false.

HTML

<!DOCTYPE html>  
<html>  
  
<head>  
    <!-- Loading the FabricJS library -->
    <script src=  
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js">  
    </script>  
</head>  
  
<body>  
    <div style="text-align: center;width: 600px;">  
        <h1 style="color: green;">  
            GeeksforGeeks  
        </h1>  
        <b>  
            Fabric.js | Polygon lockScalingY Property  
        </b>  
    </div>  
  
    <canvas id="canvas"
            width="600"
            height="200"
            style="border:1px solid #000000;">  
    </canvas>  
  
    <script>  
  
        // Initiate a Canvas instance  
        var canvas = new fabric.Canvas("canvas");  
  
        // Initiate a polygon instance  
        var polygon = new fabric.Polygon([  
        { x: 295, y: 10 },  
        { x: 235, y: 198 },  
        { x: 385, y: 78},  
        { x: 205, y: 78},  
        { x: 355, y: 198 }], {  
            fill: 'yellow', 
            lockScalingY: false 
        });  
  
        // Render the polygon in canvas  
        canvas.add(polygon);  
    </script>  
</body>  
  
</html>

Output:

Example 2: In this example, lockScalingY value is set to true.

HTML

<!DOCTYPE html>  
<html>  
  
<head>  
    <!-- Loading the FabricJS library -->
    <script src=  
"https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.6.2/fabric.min.js">  
    </script>  
</head>  
  
<body>  
    <div style="text-align: center;width: 600px;">  
        <h1 style="color: green;">  
            GeeksforGeeks  
        </h1>  
        <b>  
            Fabric.js | Polygon lockScalingY Property  
        </b>  
    </div>  
  
    <canvas id="canvas"
            width="600"
            height="200"
            style="border:1px solid #000000;">  
    </canvas>  
  
    <script>  
  
        // Initiate a Canvas instance  
        var canvas = new fabric.Canvas("canvas");  
  
        // Initiate a polygon instance  
        var polygon = new fabric.Polygon([  
        { x: 295, y: 10 },  
        { x: 235, y: 198 },  
        { x: 385, y: 78},  
        { x: 205, y: 78},  
        { x: 355, y: 198 }], {  
            fill: 'yellow', 
            lockScalingY: true 
        });  
  
        // Render the polygon in canvas  
        canvas.add(polygon);  
    </script>  
</body>  
  
</html>